1. Field of the Invention
The present invention relates to an optical fiber reel and an optical fiber storing case for storing an optical fiber used for optical wiring in optical communication equipment such as an optical amplifier. And further, the present invention relates to an optical repeater using the optical fiber reel and the optical fiber storing case.
2. Description of the Related Art
Fusion splicing is generally used to splice optical fibers used for optical wiring in an optical communication equipment. Diameter of an optical fiber is, for example, 125 xcexcm and diameter of a core in which light propagates is more small of about 10 xcexcm. It is necessary to set end portions of the optical fibers to be spliced into an fusing apparatus with high accuracy in order to carryout fusion splicing. An optical fiber needs, therefore,excess length part of it adding with practically using part. Especially in optical communication equipment such as an optical amplifier where a number of optical fibers are wired and spliced, it is necessary to efficiently house the excess length parts of the number of optical fibers in a limited space. And therefore various storage cases for excess length part of an optical fiber have been proposed.
For example, Japanese Laid-Open Patent Publication 174238/1999 discloses a storage case for an optical fiber fusion splicing part. FIG. 24 and FIG. 25 are oblique drawings showing a condition of using a storage case for the fusion splicing part of an optical fiber. In the drawings, numeral 101 is a case body, numeral 102 is a lid, numeral 103 is a take-up member, numerals 104 and 106 are through holes, numerals 105 and 107 are introduction openings, and numeral 108 is a rotary disc. Numeral 10 is a reinforce sleeve, and the reinforce sleeve 10 is generally used to cover the surrounding of fused end parts of optical fibers which are spliced by facing their end parts to another fiber""s end parts. Numerals 14 and 15 are take-up holes, numeral 16 is a holding sheet, numeral 17 is a cut line of the holding sheet 16, and L is a core, i.e., an optical fiber.
The take-up member 103 has a groove at a center portion in which the sleeve can be inserted only from one side, to fit a reinforce sleeve 10(not shown in the drawings, but is located at the same position of the reinforce sleeve 10). And the take-up member 103 including two take-up parts having outer circumferential take-up face with a radius of curvature not less than the bend minimum radius of the core L.
The rotary disc 108 has an outsider diameter larger than the major axis of the take-up member 103 and is formed integrally to have the same axis as the take-up member 103, on a face opposite to the opening side of the groove to fit a reinforce sleeve 10.
The holding sheet 16 is divided into two sheets at the center portion and having external configuration larger than that of the take-up member 103. And the holding sheet 16 is stuck to the take-up member 103 at the opening side of the groove to fit a reinforce sleeve 10.
The take-up holes 14 and 15 are forming of a pair of through halls of the rotary disc 108, forming on the two take-up parts of the take-up member 103 with the groove to fit a reinforce sleeve 10 as the center.
The case body 101 and the lid 102 are made to removable from each other. The case body 101 has a core introduction opening 105 and the lid 102 has a core introduction opening 107. And the introduction openings 105 and 107 are made on outer circumferential portions in a tangent direction of the case body 101 and the lid 102 respectively. In a storage portion, comprising the case body 101 and the lid 102, the take-up member 103 is rotatably stored.
Excess length parts of optical fibers including a fusion splicing part are stored in this storage case for a fusion splicing part of an optical fiber as described below. First, as shown in FIG. 24, the lid 102 of the storage case is opened and the slide disk 108 comprising the take-up member 103 is taken out. Then, the reinforce sleeve 10 serving as the fusion splicing part of the core L is inserted from the cut line 17 of the holding sheet 16 which is on the take-up member 103 and is fixed at the reinforcing sleeve fitting groove.
Next, as shown in FIG. 25, the cores L extending from the end portions of the reinforce sleeve 10 are placed inside through the introduction openings 105, and the lid 102 is closed. Then, with the storage case held, the rotary disc 108 is rotated in a take-up direction utilizing the take-up holes 14, 15. Thus, the cores L are retracted from the introduction openings 105, 107 successively, and the excess length parts of the cores(optical fibers) L come to be stored in the case.
However, in the above mentioned conventional storage case for a fusion splicing part of an optical fiber, the reinforce sleeve 10 serving as the fusion splicing part is fixed into the case. It is, therefore, essential that the difference between the excess lengths of the optical fibers on both sides of the reinforce sleeve 10 are a predetermined length. In other words, if the difference between the excess lengths of the optical fibers on both sides of the reinforce sleeve 10 are not the predetermined length, one of the excess length parts is not stored in the case and is left outside or one side of the optical fiber is pulled strongly as to break off and another side of the optical fiber can not be pulled sufficiently to store the case.
And yet under normal conditions, the rate of succeeding in fusion splicing of optical fibers (the rate of succeeding in fusion splicing in the first attempt and going straight to the next process) is not always 100%. In most cases, it is necessary to cut and fuse again the fusion portion, and actually it is almost impossible to accurately determine the excess lengths of the optical fibers.
Moreover, in the conventional storage case for excess length part of an optical fiber, to store excess length parts of optical fibers with a number of the reinforce sleeve 10, the same numbers of the case bodies 101, 102 are required. Therefore, it is necessary that a thickness of each case body 101, 102 is larger than a diameter of the reinforce sleeve 10 and, as a result, a large storing space is required.
The present invention was made to solve the above mentioned problems incidental to the prior art and to provide a compact storage case for excess length part of an optical fiber, even if the excess lengths of an optical fiber is not determined, optical fibers are neatly stored without being left outside.
An optical fiber reel according to the present invention, which is a reel for storing an optical fiber, comprises two optical fiber take-up members taking up an optical fiber and two flat plate like frame members sandwiching the two optical fiber take-up members between them, the two flat plate like frame members, covering the two optical fiber take-up members, having external circumferential configuration of which diameter is larger than diameter of a circumscribed circle of the two optical take-up members by not less than three times of d of diameter of the optical fiber, and arranged facing each other to make a gap not less than d but less than 2d, each of the two optical fiber take-up members having an external circumferential take-up face and a pair of outer surfaces, and arranged as the pair of outer surfaces being parallel to a flat plate face of the frame members to make a gap of not less than d between each other external circumferential take-up faces of the take-up members, the external circumference of the plane like frame members and external circumferential take-up faces of the optical fiber take-up members constituting to make a gap of not less than d between them.
It is preferable that center point of the frame members having the circular outer circumferential configuration is located to coincide with a point of symmetry of the optical fiber take-up members.
It is also preferable that each optical fiber reel has a construction in which two discs, having projections as the optical fiber take-up members, can be joined at each other projections.
It is also preferable that the outer circumference of the optical fiber take-up member is circular.
It is also preferable that the outer circumferential configuration of the optical fiber take-up members comprises: two first convex circular arcs which are located from the vicinity of center point of the frame members to the outer circumferential portion and have a radius R of less than one quarter of the diameter of the frame member; a concave circular arc which extends from a side end portion of the center point of one of said first convex circular arcs along the neighboring other first convex circular arc and has a radius of not less than R+d; and a curve which includes a second convex circular arc having a radius of not less than 2R and connects an outer circumferential side end portion of the frame member of said concave circular arc and an outer circumferential side end portion of the frame member of said first convex circular arc.
It is also preferable that the frame members are 0.1 mm to 0.3 mm in thickness.
It is also preferable that the rotation locking mechanism comprises a lid which pushes the stacked optical fiber reels in a stacking direction and a pillar member which pushes a part of the outer circumferences of the frame members of the stacked optical fiber reels, stacking from the introduction opening formed on an outer circumferential portion of the case body, toward the center point.